1. Field of the Invention
This invention relates to a refrigeration purging system and process and in particular to a system designed to remove non-condensibles and contaminants which collect within the refrigeration system.
2. Description of the Prior Art
Within refrigeration systems various non-condensible gases and contaminants become mixed with the refrigerant and tend to collect at some point such as the top of the condenser. The presence of non-condensibles and contaminants in the system reduces the efficiency of the system since they necessitate higher condenser pressures with accompanying increases in power cost and cooling water consumption. The capacity of the system is also reduced since the non-condensible gases displace refrigerant vapor. Purging devices of various types have been used to remove or purge the non-condensibles and contaminants from the system.
Such devices normally include a purge chamber for collecting the non-condensibles, such as air and other non-condensible gases, and expelling them to the atmosphere. The gases which collect in the purge chamber also include water vapor and portions of the refrigerant vapor. A heat transfer coil located within the purge chamber is supplied with a cold water or cool liquid refrigerant and operates as a condensing coil to condense the refrigerant and water vapor to a liquid. The condensible gaseous constituents such as refrigerant and water are removed from the chamber and then recirculated to the refrigeration system or expelled from the system. The non-condensible gases are usually vented to the atmosphere by a pump which operates in response to the pressure differential between the purge chamber and the refrigerant condenser. In purge systems of the above-described type, a certain amount of refrigerant which is not condensed within the purge chamber is exhausted to the atmosphere together with the non-condensibles. The evacuated gases contain, on the average, one part of non-condensibles and three parts of refrigerant. It is desirable to significantly reduce the refrigerant expelled during the purging operation since refrigerant is expensive to replace and is an undesirable contaminant in the environment.